1. Field of the Invention
The present invention relates to an apparatus for roll-changing.
2. Description of the Prior Art
Reversing mills and tandem mills are generally known as rolling mills. With respect to one stand thereof, 2-high rolls, 4-high rolls, 6-high rolls and 20-high rolls are common mill systems.
The old conventional method for changing rolls in a 4-high roll stand, comprised, for example, removing work rolls from the mill stand one by one and transporting them in a two high configuration.
Recently, the steps of changing rolls in a 4-high mill have comprised using a roll-changing truck to transport the work rolls in a two high configuration, and in a 6-high mill, transporting the work rolls and intermediate rolls, totalling four rolls, in a four high configuration.
In the conventional method for changing the rolls of a rolling machine employing a roll-changing truck, the steps of loading of the reconditioned rolls from a roll storage shed within the roll shop onto a roll-changing truck and the unloading of the worn rolls from the roll-changing truck at the storage shed have been carried out by means of a dedicated hoist employing a crane. Moreover, as described in Japanese published unexamined patent application No. 114363/1976, those operations have been carried out by a combination of a conveyor and a hoist, and the rolls are placed at rest one high on a rack at the roll storage shed. Furthermore, Japanese published examined patent application No. 56564/1985 discloses a roll-changing device in which one set of top and bottom work rolls and top and bottom intermediate rolls are transported on rails, and the rolls are placed one high on a rack at the roll storage shed. In this case, in changing of one set of rolls for another, the crane can hoist only one or two rolls at most.
According to the aforementioned conventional method, during transport of the rolls, it is necessary for someone on the ground to give a signal to the crane, and when the roll-changing truck and the roll storage shed are separated it is further necessary for a truck to travel between the two locations. Still further, the maximum number of the rolls that can be carried at one time is only one or two and, accordingly, much labor and time have been required for carrying the set of four rolls (two working rolls and two intermediate rolls) of the rolling machine at one time.
Still further, according to such a conventional method of using a crane for carrying the rolls between the roll-changing truck and the roll storage shed within the shop, it was necessary for a hooking operator to be able to work freely so that the roll shop inevitably occupied a large area.